P5091

In conclusion, USP7 was a key regulator of DNA repair in pNENs. The combination of cisplatin and P005091 therefore holds promise as a therapeutic strategy for pNENs.

Recent studies indicate that multiple Ubiquitin-Specific Proteases (USP) family members play pivotal roles in lung cancer: Ubiquitin-Specific Peptidase 7 (USP7) promotes proliferation and osimertinib resistance in non-small cell lung cancer by stabilising proteins such as ERβ, c-Abl, and KRAS; Ubiquitin-Specific Peptidase 9, X-linked (USP9X) mediates radiotherapy resistance by regulating KDM4C and REV1; USP10 influences cellular metabolism and chemotherapy sensitivity via PTEN/AKT/mTOR and HDAC6 pathways; Ubiquitin-Specific Peptidase 14 (USP14) enhances tumour migration by regulating β-catenin and Acf7 stability; Ubiquitin-Specific Peptidase 22 (USP22) amplifies tumour stem cell properties and suppresses ferroptosis via EGFR and BMI1 signalling; Ubiquitin-Specific Peptidase 35 (USP35) and Ubiquitin-Specific Peptidase 38 (USP38) respectively modulate apoptosis resistance and proliferation through BIRC3 and KLF5; while Ubiquitin-Specific Peptidase 39 (USP39) influences mitochondrial metabolism via PDHA, thereby promoting tumour growth...It further explores the potential value of small-molecule inhibitors targeting USPs (such as P5091, IU1, and gentiopicroside) in reversing drug resistance, inducing apoptosis, and enhancing immunotherapy...This paper reviews the molecular mechanisms and targeting strategies of USPs in lung cancer based on a systematic literature search of PubMed and Web of Science databases. It further explores their potential applications in precision lung cancer therapy, providing theoretical foundations and directional guidance for future research.

Given USP7's role in oxidative stress and ferroptosis, we examined its involvement and found that P5091 induced ferroptosis via reactive oxygen species (ROS) elevation, glutathione peroxidase 4 (GPX4) downregulation, and elevated lipid peroxidation. These findings demonstrate that USP7 inhibition by P5091 enhances PLX4032 efficacy by promoting tumor suppression and ferroptosis in BRAFV600E-mutant thyroid cancer, offering a promising strategy to overcome resistance.

USP47 is essential for modulating proliferation, migration, invasion, and immune evasion of HCC cells. Inhibiting USP47 in combination with PD-1 blockade can enhance the suppression of HCC growth, potentially holding clinical importance. This investigation elucidates the role of USP47 in PD-L1 stability via deubiquitination, offering a new prognostic indicator and potential target for treating HCC.

This study sheds light on the molecular mechanisms underlying the Warburg effect in PDAC and unveils USP7 as a potential therapeutic target for improving PDAC treatment.

Furthermore, USP7 inhibitor P5091 also diminished CCSCs self-renewal and reduced mutant p53 levels. Taken together, our findings demonstrated that USP7 involved in the modulation of CCSCs stemness, as well as a critical target for clinical treatment of cancers with different p53 mutations.

Melatonin, a hormone that inhibits glucose intake, markedly suppressed cell proliferation of p53 wild-type NSCLC, while a combination of melatonin and the USP7 inhibitor P5091 enhanced the anticancer activity in p53-deficient NSCLC. Our collective findings support a role of PRMT1 in the regulation of Warburg effect in NSCLC. Moreover, combination treatment with melatonin and the USP7 inhibitor showed good efficacy, providing a rationale for the development of PRMT1-based therapy to improve p53-deficient NSCLC outcomes.

We showed that knockdown of USP7 or treatment with USP7 inhibitor P5091 suppressed liver cancer growth by promoting CD8+ T cell activity in Hepa1-6 xenograft mice and in HepG2 or Huh7 cells co-cultured with T cells, whereas USP7 overexpression produced the opposite effect...In an immunocompetent liver cancer mouse model, the dual blockade of USP7 and LAG3 resulted in a superior antitumor activity compared with anti-LAG3 therapy alone. We conclude that USP7 diminishes CD8+ T cell activity by a USP7/PRDM1 positive feedback loop on FGL1 production in liver cancer; USP7 might be a promising target for liver cancer immunotherapy.

However, the chemoresistance of cancer cells to USP7i (P22077 and P5091) and mechanisms to overcome it have not yet been investigated. Inhibition of HSF1 and PERK significantly sensitized cancer cells to USP7i-induced cytotoxicity. Our study demonstrated that the ER stress-PERK axis is responsible for chemoresistance to USP7i, and inhibiting PERK is a potential strategy for improving the anticancer efficacy of USP7i.

Treatment of the CLL cell line MEC1 and primary CLL patient samples with DUB inhibitors including PR-619 (pan-DUBi), P5091 (USP7i) and HBX19818 (USP7i) alone reduces the phosphorylation of AKTS437 and FOXO1T24, indicating that DUBs play a role in inhibiting FOXO1 activity. Additionally, FOXO1 activity studies demonstrated significant activation of FOXO1 upon ibrutinib treatment, which was further enhanced in the USP7 KD and combination with USP7i. These studies suggest that selective DUBs play a role in BCR-mediated signalling to aid in the promotion of CLL cell survival and chemo-resistance through FOXO1 inhibition, and targeting these DUBs enhance FOXO1 activity leading to cell cycle arrest and apoptosis.

Pharmacological inhibition of USP7 by P5091 phenocopies the shUSP7-induced senescent phenotype. We show that the bifunctional histone deacetylase (HDAC)/LSD1 inhibitor domatinostat has an additive antitumor effect, eliminating P5091-induced senescent cells, paving the way to a therapeutic combination for individuals with melanoma.